There are two methods for the measurement principle of the dissolved oxygen analyzer, do you know?
Molecular oxygen dissolved in water is called dissolved oxygen, and the amount of dissolved oxygen in water is an index to measure the self-purification ability of water body.
The dissolved oxygen value is a basis for studying the self-purification ability of water. The dissolved oxygen in the water is consumed, and it takes a short time to return to the original state, indicating that the water body has a strong self-purification ability, or the water body is not seriously polluted. Otherwise, it means that the water body is seriously polluted, the self-purification ability is weak, or even loses the self-purification ability.
Water quality dissolved oxygen online analyzer is an intelligent online analysis equipment for the analysis of dissolved oxygen in water quality. Its measurement principle is divided into polarographic film method and optical fluorescence method.
1. Polarographic film method:
The principle is that the solubility of oxygen in water depends on the temperature, pressure and the salts dissolved in the water. Its sensing part is composed of gold electrode (cathode) and silver electrode (anode) and KCl or potassium hydroxide electrolyte. Oxygen diffuses through the membrane into the electrolyte and gold electrode and silver electrode to form a measurement circuit. When a polarization voltage of 0.6~0.8V is applied to the dissolved oxygen electrode, oxygen diffuses through the membrane, the cathode releases electrons, and the anode accepts electrons to generate current. According to Faraday's law: the current flowing through the dissolved oxygen electrode is proportional to the partial pressure of oxygen, and there is a linear relationship between the current and the oxygen concentration when the temperature is constant.
2. Optical fluorescence method:
The measurement principle of fluorescence method is the quenching effect of oxygen molecules on fluorescence. The sensing diaphragm is covered by a layer of fluorescent material. When a blue light source of a specific wavelength irradiates the fluorescent material on the surface of the sensing diaphragm, the fluorescent material is excited to release red light. Oxygen molecules will inhibit the fluorescence effect, so the higher the oxygen concentration in the water, the shorter the red light release time. In theory, there is a quantifiable correlation between the red light release time and the dissolved oxygen concentration, so by measuring the red light The light release time was used to calculate the dissolved oxygen concentration.
